Having no threads is exactly what makes Redis so convenient in deploying it to clusters: you have a node, and the node is a single process. It's like a building block.
Also, Redis source code is so much cleaner than memcached!
And yet it works incredibly well and is indispensable for many organizations.
It's almost like less sometimes really is more, and that prioritizing simplicity of implementation does more than just make code maintainable--holding that value as a developer can "leak" all the way up to the reliability of your software, in the best possible way.
Yeah, let's code like it's 1970's and multi-core CPUs are Sci-Fi ;)